Throughout this application various patents and publications are referenced, many in parenthesis. Full citations for each of the referenced publications are provided at the end of the Detailed Description. The disclosures of each of these patents and publications in their entireties are hereby incorporated by reference in this application.
It is estimated that in 1992, 35.2 million wounds required major therapeutic intervention in the US (Medical Data International, Inc. 1993). Surgical incisional wounds are performed with aseptic technique, and are closed by primary intention. Most repair and heal uneventfully. Many traumatic wounds and cancer extirpations, however, must be left open to heal by secondary intention. Furthermore, chronic wounds have significant tissue necrosis and fail to heal by secondary intention. It is estimated that 5.5 million people in the US have chronic, nonhealing wounds and that their prevalence is increasing secondary to the increase in age-related diseases, the increase in Acquired-immune Deficiency Syndrome (“AIDS”), and the increase of radiation wounds secondary to cancer intervention. In the US, approximately 1.5–2.5 million people have venous leg ulcers; 300,000–500,000 people have diabetic ulcers; and 2.5–3.5 million people have pressure ulcers (Callam et al. (1987); Phillips and Dover (1991); Lees and Lambert (1992); Lindholm et al. (1992)). These acute and chronic open wounds require long-term care and procedures that include skin grafting and tissue flaps, debridement, frequent dressing changes, and administration of pain medications. This care is costly and labor intensive. Furthermore, these wounds have a severe impact on the patients' quality of life. The chronic dermal ulcerations can cost as much as $40,000 each to heal, and more disappointing is that 50% reappear within 18 months of healing. Chronic dermal ulcers are also associated with mortality. As many as 21% of patients in intermediate-care facilities with pressure ulcers die (Bergstrom et al. (1994)).
Although multiple millions of dollars have been spent on the development of numerous recombinant growth factors (Abraham and Klagsbrun (1996); Heldin and Westermark (1996); Nanney and King (1996); Roberts and Sporn (1996)) and organotypic skin replacements (Boyce et al. (1995)) for use in open wounds over the past decade, the evidence of cost-effective benefit is meager thus far (Brown et al. (1989); Robson et al. (1992a); Robson et al. (1992b); Phillips et al. (1993)).
Many attempts have been made to produce a composition which can be used to facilitate wound repair.
Many of these compositions involve collagen as a component. U.S. Pat. Nos. 4,950,483 and 5,024,841 each discuss the usefulness of collagen implants as wound healing matrices. U.S. Pat. No. 4,453,939 discusses a wound healing composition of collagen with a fibrinogen component and a thrombin component, and optionally fibronectin. U.S. Pat. No. 4,970,298 discusses the usefulness of a biodegradable collagen matrix (of collagen, hyaluronic acid, and fibronectin) for wound healing. Yamada et al. (1995) disclose an allogeneic cultured dermal substitute that is prepared by plating fibroblasts onto a spongy collagen matrix and then culturing for 7 to 10 days. Devries et al. (1995) disclose a collagen/alpha-elastin hydrolysate matrix that can be seeded with a stromal-vascular-fraction of adipose tissue. Lamme et al. (1996) disclose a dermal matrix substitute of collagen coated with elastin hydrolysate. U.S. Pat. No. 5,489,304 and Ellis and Yannas (1996) each disclose a collagen-glycosaminoglycan matrix.
There are also numerous compositions which involve hyaluronic acid (“HA”) as a component. Ortonne (1996), Borgognoni et al. (1996), and Nakamura et al. (1997) each discuss the usefulness of HA for wound healing. In Nakamura et al. (1997), HA was combined with chondroitin sulfate in one series of experiments. In U.S. Pat. No. 5,604,200, medical grade HA and tissue culture grade plasma fibronectin were used in combination with calcium, phosphate, uric acid, urea, sodium, potassium, chloride, and magnesium to create a moist healing environment that simulates the fetal in utero wound healing matrix. U.S. Pat. No. 5,631,011 discloses a composition of HA and fibrin or fibrinogen.
Various other compositions have also been explored for their wound healing capabilities. Kratz et al. (1997) used a gel of heparin ionically linked to chitosan. Bartold and Raben (1996) studied platelet-derived growth factor (“PDGF”). Henke et al. (1996) disclosed that chondroitin sulfate proteoglycan mediated cell migration on fibrinogen and invasion into a fibrin matrix, while Nakamura et al. (1997) concluded that chondroitin sulfate did not affect wound closure in a corneal epithelial wound. Henke et al. (1996) also disclosed that an anti-CD44 antibody blocked endothelial cell migration on fibrinogen. U.S. Pat. No. 5,641,483 discloses topical gel and cream formulations containing human plasma fibronectin for healing cutaneous wounds. Schultz et al. (1992) discloses a composition of epidermal growth factor (“EGF”), fibronectin, a synthetic collagenase inhibitor, and Aprotinin.
Fibrin matrices and components of fibrin matrices have been investigated for promoting wound healing. Besides being the ultimate plug of the hemostasis system, fibrin is part of a provisional matrix that provides tissue cells a scaffold for repopulation of a wound (Clark et al. (1982a)). Recently, however, it was discovered that fibroblasts, tissue mesenchymal cells, will not penetrate a pure fibrin clot (Greiling and Clark (1997)). Another plasma protein, fibronectin, normally found in blood clots must be present in the clot for fibroblast migration (Greiling and Clark (1997)).
Some fibrinogen preparations have been found to improve healing. Fibrin sealants, or glues, are topical, biologically compatible, resorbable tissue adhesive that initiate the last phases of coagulation during wound healing. The components of fibrin sealants typically consists of concentrated human fibrinogen in solution with various amounts of fibronectin and factor XIII, as well as other components. The fibrin sealants are activated by addition of thrombin and calcium chloride and subsequently form a coagulum (clot). Methods of obtaining the concentrated fibrinogen include precipitation of plasma by cryroprecipitation, polyethylene glycol or ammonium sulphate (Brennan (1991)). Contradictory results are obtained, however, for these preparations. In some instances, the fibrinogen preparations improve healing (Gelich et al. (1995); Saclarides et al. (1992), in others no improvement in healing was found (Lasa et al. (1993); Byrne et al. (1992). Further, animal studies have not been predicative of clinical use. In addition, the fibrin sealants utilized to date vary in purity levels.
In view of the severity of the problem of chronic, nonhealing wounds, new and more effective matrices and methods for facilitating wound healing, and in particular, fibroblast migration are needed. The present invention is directed to meeting this need.